Shaft driven bicycles date back to 1890... the major issue is that they are not as efficient as a chain driven bicycle and the shaft drive is more complex and more expensive to produce and the bicycles that use them are specifically designed to use them.

They have their place as they enclose the drive train and as such, are not subject to contamination.

I had one that I posted about a few threads back.
To me, built-in design flaw. Not too much to overcome with grease and locktite.
Great Idea, execution of, not so much. If you live in a muddy/inclimate weather place
or you've gotten greased by a chain carrying your bike up three flights of stairs, you will
appreciate the design.

The web site says the life of the drive is 6-8k miles. Less for aggressive or heavy riders. I have to suspect that replacing it is considerably more than the cost to replace a chain. I'm not impressed by that lifetime. I get around 3k+ out of a chain.

A few people here have had Dynamics in the past and have posted that the drive is not that great. It's not efficient, the shaft can tend to torque giving a springy feel to the drive, and the bevel gears break much more easily than chains.

You can't use the lightest weight and most efficient transmission ever devised, the rear derailleur, so if you want gears, you have to use an internal hub, which adds even more inefficiency and another pound or two of weight.

Also, changing a flat tire on it is said to be a chrome plated pain in the rear.

Their claim for "simpler to maintain" is correct in a way. You don't have to do frequent service, no chain oiling every weekend, etc. You just have to buy and bolt on a whole new shaft assembly every 8000 miles or so, at I'm sure many times the price of a new chain every 5K or so.

Apparently the primary market for Dynamic bicycles is beach resort cruiser rentals, where an enclosed drive train that can't get grease on your clothes is more important than efficiency, and rebuilding the drivetrain every year or two in the off season for 50 bikes isn't a big deal.

If there's a "future" that doesn't involve a standard chain drive, I'd bet on belt before shaft.

At Henry Ford Village (part of Henry Ford Museum) in Dearborn, MI, they have Orville and Wilbur Wright's bicycle shop where they built the Wright Flyer - the actual shop, they moved it there (along with some buildings from Menlo Park). One of the things they have in there is a shaft drive bike from the 1890s. The actor's script goes on about how this is some kind of miracle thing that is clearly better than what we use now and just is waiting to be rediscovered. After he finished and people were going through, I approached him and said I knew he was just doing his job, but people do make shaft drive bicycles today, and there's a real good reason why they don't sell very well.

A few people here have had Dynamics in the past and have posted that the drive is not that great. It's not efficient, the shaft can tend to torque giving a springy feel to the drive, and the bevel gears break much more easily than chains.

This was the design flaw I mentioned earlier. I think the shaft itself will last indefinitely, but the way Dynamic put it together is what makes it a disposable bike. The whole unit is held together by only 3, small screws of about 3mm thread diameter, combined with only what I would estimate to be 2mm's of overlap on the bevel gears. Those three very important screws come loose regularly, when they do, the gears chip and gnash due to the lack of overlap in the bevel gears, eventually rendering them useless. The gears should have been spec'd with more overlap and there should be at least five larger allen screws or bolts clamping the the bottom bracket machinery together.

The same GT Outpost Mountain bike I've been riding since 1996, although I modify it throughout the year for commuting, touring, and recreational riding. I also have a collection of cruisers, folders, and some antiques.

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Well, one good purpose bikes like these serve is to remind us of how much we'd like to see the end of chain/derraileur-driven bicycles. As I get older and less willing to get down on my knees and grease up my hands, I'm more and more anxious to find a bike that's easier to maintain.

Papa Tom

"I just need a rest...and by 'rest' I mean a really long bicycle ride."

The same GT Outpost Mountain bike I've been riding since 1996, although I modify it throughout the year for commuting, touring, and recreational riding. I also have a collection of cruisers, folders, and some antiques.

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Belt drive? Yeah, but still too many exposed parts. And what does it take to clean that belt? Also, what do you do when it snaps in the middle of a journey and you don't have a spare?

Papa Tom

"I just need a rest...and by 'rest' I mean a really long bicycle ride."

jan.25 019.jpgWell, So many out there don't understand simple mechanics... Its a great design . It does not have rowcipracating mass. its harder to keep pedaling, But as for the wear lifetime, don't know I will tell youzguys later. and they offer a lifetime warranty on defects who gives that out?
Give it a try ! school 032.jpgAnd just think about a centrificial clutch and a electric motor Im working on that...
When in doubt gas it out....

Dynamic claims they are now using a fourth generation Sussex shaft drive system. I have no idea how this is different from earlier iterations or whether the descriptions related in this thread are of this latest design or previous ones.

At any rate, Major Taylor not only competed on shaft drive cycles, he won races and set records with them.

"When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

"Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

Dynamic has an intriguing picture on their web site of shaft drive bike share (bike rental) machines. While I have some questions and concerns about their currently proposed implementation, as a concept, I think that has a lot of promise.

"When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

"Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008

Belt drive? Yeah, but still too many exposed parts. And what does it take to clean that belt? Also, what do you do when it snaps in the middle of a journey and you don't have a spare?

I used PAM vegetable pan spray on my Harley's belt. The same type of belts have been used on high horsepower motorcycles for a long time. They are proven.
I would be willing to be that there has never been a broken belt on a belt on a bicycle, ever.
I would trust a belt way more than a chain. But this is BF, someone is always going to disagree with you

Motorcycles have... and have had shaft, chain, and belt drives. Having both hub gears and chain and cogs isn't anything new to bicycles. Bringing back a bicycle with a driveshaft and adding bicycles with belts just gives cyclist more options.

I don't expect to see a one type fits all bicycle in my lifetime. Even with all the progress and changes in the last few years.... I can still buy a steel single speed bicycle nearly identical to what I owned over half a century ago.

I have a Dynamic, a 2012 Runabout 7. I've posted a pretty detailed review of it here on BF before.

It's been a pretty good bike for me. I am a full-time bicycle commuter, and commuting is at least 95% of my mileage. Currently, I use the Dynamic as my backup bike. It has 1800 miles on it and still going strong. Last year, I bought a 2013 Jamis Commuter 3 at the LBS I really like, and the Jamis is my #1 . Both bikes have the same Shimano 7-speed IGH, which I absolutely love. Honestly, I think these two bikes are closer to each other than either would be to a bike with derailleurs and a traditional setup.

My Jamis is faster and has better geometry for me, so it is my #1 . The Dynamic is actually lower maintenance though, and changing a rear tire flat on the chainless is much easier than on the chain bike.

The Jamis has the advantage of being the line carried by the LBS I shop at. Don't underestimate the benefits of buying from the line your LBS sells, if you can find a LBS you really like that gives great service. I didn't get a Jamis because of brand identification, advertising, or such. I got one because I have a great wheelbuilder I found who runs a little bike shop, and Jamis is the brand he sells. I put together a list of specifics I wanted (with the 7-speed IGH at the very top of the list), and we went through the Jamis models and picked the Commuter 3. The buying and post-sales service have been great experiences. I say all that because if you go with an internet order bike like Dynamic, you miss some of that experience. If you don't have a local LBS you like, or if they are willing to assemble a Dynamic, maybe that is not a big deal to you.

Belt drive? Yeah, but still too many exposed parts. And what does it take to clean that belt? Also, what do you do when it snaps in the middle of a journey and you don't have a spare?

25K miles on my 95cui Harley,zero issues. Only time I've ever tensioned the belt was after changing the rear tire. Once got a stone in it that 'dented' some of the belt teeth. Kept an eye on it,and after a couple hundred miles the dents went away. That was like 15k miles ago. Never did anything to it other than wipe it with a rag after washing the bike.

Another issue with shaft drives on bicycles: changing your gearing. With chain/belt you just swap a cog/ring/pulley. With shaft drive,you're stuck with what you've got.

I used PAM vegetable pan spray on my Harley's belt. The same type of belts have been used on high horsepower motorcycles for a long time. They are proven.
I would be willing to bet that there has never been a broken belt on a belt on a bicycle, ever.

Cyclists don't generate much horsepower but they do have quite a bit of torque. And presumably the belts for bicycles are made lighter than those on heavier and more powerful vehicles.

I guess I should have known there would be some broken ones somewhere, but the post clearly states the rider reinstalled the belt in a manner that was specifically against the installation instructions. I have broken a chain on a bicycle (and motorcycle)before and it was a most unpleasant situation Maybe thats why Im a little more open to the idea of a belt being less problematic.

Related to the OP, I looked on Dynamics site today just out of curiosity and it seems they remedied one of the issues that was a negative with my shafty, that being only three small screws holding the whole unit together. I looks like there is 6 now.

I thought about going belt drive with my most recent bike purchase - I picked up a Giant Seek 0 2014, which is IGH chain drive. I could have gotten the Trek Soho with the same hub but belt drive (and mechanical instead of hydro brakes) for $200 more, but I decided that given that it has a chain case, I don't really care that much. With single speed, there's no reason in the world why the chain won't last 10,000 to 20,000 miles without much attention.

"When man first set woman on two wheels with a pair of pedals, did he know, I wonder, that he had rent the veil of the harem in twain? A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Typewriter Girl, 1899.

"Every so often a bird gets up and flies some place it's drawn to. I don't suppose it could tell you why, but it does it anyway." Ian Hibell, 1934-2008